机器学习-CoreML人脸识别

Swift


使用Vision框架进行人脸识别，不仅可以识别出人脸的面部轮廓，还可以识别出人脸的特征点，比如眼睛、鼻子、嘴巴等。进行人脸请求的类是VNDetectFaceRectanglesRequest，人脸特征请求的类是VNDetectFaceRectanglesRequest,请求结果的信息类是VNFaceObservation。下面直接上代码。

  1. 搭建基本UI

  1. 识别面部轮廓
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func processImage(image:UIImage) {
       self.resultLabel.text = "processing..."
       let handler = VNImageRequestHandler.init(cgImage: image.cgImage!)
       let request = VNDetectFaceRectanglesRequest.init(completionHandler: handleFaceDetect)
       try? handler.perform([request])
   }
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func handleFaceDetect(request:VNRequest,error:Error?) {
        guard let obversations = request.results as? [VNFaceObservation] else {
            fatalError("no face")
        }
        self.resultLabel.text = "\(obversations.count)face"

        for subView in self.btnImageView.subviews where subView.tag == 100 {
            subView.removeFromSuperview()
        }
        
        for faceObversion in obversations {
            self.showFaceContour(faceObversion: faceObversion, toView: self.btnImageView)
            
    }
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func showFaceContour(faceObversion face : VNFaceObservation, toView view : UIView) {
    let boundingBox = face.boundingBox
    let imageBoundingBox = view.bounds
    
    let w = boundingBox.size.width * imageBoundingBox.width
    let h = boundingBox.size.height * imageBoundingBox.height
    
    let x = boundingBox.origin.x * imageBoundingBox.width
    let y = imageBoundingBox.height - boundingBox.origin.y * imageBoundingBox.height - h
    
    let subview = UIView(frame: CGRect(x: x, y: y, width: w, height: h))
    subview.layer.borderColor = UIColor.green.cgColor
    subview.layer.borderWidth = 1
    subview.layer.cornerRadius = 1
    subview.tag = 100
    view.addSubview(subview)
}
  • 相当于在人脸上画了一个轮廓视图添加上去。boundingBox是CGRect类型，但是boundingBox返回的是x,y,w,h的比例(value:0~1)，需要进行转换。原始坐标系的原点是左上角，而这里是左下角，并且y轴的方向和原始坐标系相反。

3.面部轮廓展示

4.识别面部特征

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func processImage(image:UIImage) {
       self.resultLabel.text = "processing..."
       let handler = VNImageRequestHandler.init(cgImage: image.cgImage!)
       let request = VNDetectFaceLandmarksRequest.init(completionHandler: handleFaceDetect)
       try? handler.perform([request])
   }

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func handleFaceDetect(request:VNRequest,error:Error?) {
       guard let obversations = request.results as? [VNFaceObservation] else {
           fatalError("no face")
       }
       self.resultLabel.text = "\(obversations.count) face"

       var landmarkRegions : [VNFaceLandmarkRegion2D] = []
       
       for faceObversion in obversations {
           landmarkRegions += self.showFaceFeature(faceObversion: faceObversion, toView: self.btnImageView)
           resultImage =  self.drawOnImage(source: self.resultImage,
                                             boundingRect: faceObversion.boundingBox,
                                             faceLandmarkRegions: landmarkRegions)
       }
self.btnImageView.setBackgroundImage(resultImage, for: .normal)
}

获取特征点

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func showFaceFeature(faceObversion face: VNFaceObservation, toView view: UIView) ->[VNFaceLandmarkRegion2D] {
        guard let landmarks = face.landmarks else { return [] }
        var landmarkRegions: [VNFaceLandmarkRegion2D] = []
        if let rightEye = landmarks.rightEye {
            landmarkRegions.append(rightEye)
        }
        if let nose = landmarks.nose {
            landmarkRegions.append(nose)
        }
        return landmarkRegions
    }

重新绘制图片（含面部特征）

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func drawOnImage(source: UIImage,
                   boundingRect: CGRect,
                   faceLandmarkRegions: [VNFaceLandmarkRegion2D]) -> UIImage {
      UIGraphicsBeginImageContextWithOptions(source.size, false, 1)
      let context = UIGraphicsGetCurrentContext()!
      context.translateBy(x: 0, y: source.size.height)
      context.scaleBy(x: 1.0, y: -1.0)
      context.setBlendMode(CGBlendMode.colorBurn)
      context.setLineJoin(.round)
      context.setLineCap(.round)
      context.setShouldAntialias(true)
      context.setAllowsAntialiasing(true)
      context.setLineWidth(5.0)
      context.setStrokeColor(UIColor.black.cgColor)
      
      // origin image
      let rect = CGRect(x: 0, y:0, width: source.size.width, height: source.size.height)
      context.draw(source.cgImage!, in: rect)
      
      // face contour
      let rectWidth = source.size.width * boundingRect.size.width
      let rectHeight = source.size.height * boundingRect.size.height
      context.addRect(CGRect(x: boundingRect.origin.x * source.size.width, y:boundingRect.origin.y * source.size.height, width: rectWidth, height: rectHeight))
      context.drawPath(using: CGPathDrawingMode.stroke)
      
      // draw face feature
      context.setStrokeColor(UIColor.red.cgColor)
      for faceLandmarkRegion in faceLandmarkRegions {
          var points: [CGPoint] = []
          for i in 0..<faceLandmarkRegion.pointCount {
              let point = faceLandmarkRegion.normalizedPoints[i]
              let p = CGPoint(x: CGFloat(point.x), y: CGFloat(point.y))
              points.append(p)
          }
          let mappedPoints = points.map { CGPoint(x: boundingRect.origin.x * source.size.width + $0.x * rectWidth, y: boundingRect.origin.y * source.size.height + $0.y * rectHeight) }
          context.addLines(between: mappedPoints)
          context.drawPath(using: CGPathDrawingMode.stroke)
      }
      
      let coloredImg : UIImage = UIGraphicsGetImageFromCurrentImageContext()!
      UIGraphicsEndImageContext()
      return coloredImg
  }

VNDetectFaceLandmarksRequest请求返回的也是VNFaceObservation，但是这个时候VNFaceObservation 对象的landmarks属性就会有值，这个属性里面存储了人物面部特征的点
如：

  • faceContour：脸部轮廓
  • leftEye、rightEye： 左眼、右眼
  • nose： 鼻子
  • noseCrest: 鼻嵴
  • outerLips、innerLips： 外唇、内唇
  • leftEyebrow、rightEyebrow: 左眉毛、右眉毛
  • leftPupil、rightPupil： 左瞳、右瞳

5.面部特征点展示



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